Hello!

I am trying to verify the maximum daily 8 hour average (MD8A) calculation for a CAMx output file (july 13 2017). My domain does not include buffer cells. I am using VERDI version 2.4.1

When I calculate MD8A directly from the CAMx netcdf output outside of VERDI, I calculate a MD8A that matches the MD8A value from AMET for that same grid cell.

When I calculate MD8A using the “maxiumum_8hour_average” stats feature in VERDI, the result shown is displaced by 1 col, 1 row. I’ve attached this image showing my analysis and comparison to VERDI:

My target monitor is in grid cell [69,78] (verified in ArcGIS). I’ve labeled my target grid cell [69,78] on the VERDI screen grab on the left. The MD8A that I calculate outside of VERDI is on the right - a screen grab from excel. Note that the MD8A calculated in excel from the CAMx netcdf for cell 69,78 matches the MD8A in VERDI for the cell 70,79.

I checked the hourly O3 values in VERDI and in my CAMx netcdf: the hourly O3 values are the exact same for the cell 69,78. Is something strange happening in VERDI when the MD8A calculation occurs? I found this in the VERDI manual, which seems like a straightforward MD8A calculation.

`* MAXIMUM_8HOUR_MEAN: Ma (M1, M2, ..., Mn-8) where Mi = mean(var(i,j,k,t(i)), var(i,j,k,t(i)+1), var(i,j,k,t(i+2)), ...,var(i,j,k,t(i+8)), for i = 1..n-8`

When I try to probe my domain for the MD8A at cell [1,1] (the southwest corner), VERDI will not produce any results. But if I probe at 2,2 and greater, it will show the MD8A.

Is there a difference occurring due to the consideration of buffer cells, perhaps? My domain does not include buffer cells.

Thanks for your help!